There is someone I know that I invited to my wedding because we are part of the same softball team and other members of the team are invited. Lately she has been treating several of my friends like crap. Now I don't want to invite her to my wedding. How do I disinvite her?
I am assuming that you have sent out the invitations and that this person has accepted.
Disinviting someone from your wedding will break your relationship with this person. If this is the intended outcome – you want them out of your life, then the answer is easier. If the person is so toxic and their presence would destroy your special day, then you have to disinvite them.
Call / email the person and let her know she is no longer invited to your wedding. It will be difficult conversation. There will likely be some anger expressed. Then hopefully the problem will be over. Future social situations with this person will probably be awkward. If this is a toxic person, you should probably avoid social situations with them anyways.
If breaking the relationship isn't the intended outcome, then you let them come to your wedding. It sounds like you have a larger guest list (you invited your softball team, and you can’t be close friends with the entire team) The large numbers allow you put them at a distant table. Perhaps sit her with the relatives you have indifferent feelings towards. Then have the bridesmaids or designated person keep an eye on her.